A Story of Alternators and Mud...and that battery light.

First a thanks to all those before me who went in the mud and posted about their battery light.

Now here is my story.

Years ago, I had 1991 Toyota 4x4 with the 22re motor. I used to get that truck covered top to bottom in mud. I’d hose off it off, pop the hood hose of the engine, and go on my way. Never had a problem with the alternator. Maybe it was dumb luck or a case of ignorance is bliss.

Flash forward. I take my 2007 TRD into some mud...a day later the battery light comes on. I hose off the engine being careful not to over hose electrical components. It begins look a lot cleaner, but the battery light...still on.

I take it to a local shop to get diagnosed. They say I need a new alternator, okay makes sense I took it through mud and now must pay the price. They say $400 for a new one, well a $300 refurbished Denso and installation. Hah! I can get a refurbished one at Auto Zone for $149, no thanks to your expensive one, I say.

I find a used one with 73k on it at TLS Auto Recycling for $40 and a one year warranty. I spend a few hours taking the old one out (125k on it - btw), put the new one in, go to start her up...battery light still on. I visually check the fuses. I spend a few hours tracing all the wires making sure there are no lose ground wires...still on.

I research forums and the net. I find a schematic online that points to a 7.5amp alternator fuse. I should double check it, I think to myself. While the fuse looked to be intact a quick test on the volt meter revealed no continuity. Ahah! A quick run to Auto Zone for a $5 pack of fuses. Problem solved! Light off!

Lessons learned:
1. Stay out of mud unless it’s necessary to get home.
2. Check fuses with a meter.
3. Don’t get ripped off by shops charging $60 to check your electrical system who couldn’t even find a $1 broken fuse.

On the bright side, I now have an alternator with a lot fewer miles, I got to know a lot about my alternator and its wiring, and spent some quality time under the hood. All in all, it costs me some time, one burn from my exhaust pipe, and $45 dollars in parts. Not too bad after all.

 

I love this post. Intelligent, well-written, good tech, and useful information. Seriously.

I really get tired of all the useless BS posts or posts that appear to be written by a 10 year old and are therefore unintelligible.

Just my 2 cents worth

 

Prob more useful in the 2nd gen area, but glad you made the mistake so I could read it before it got moved

and never will I stat out of the muds!

 

Truth.

 

Taco's do look great with a layer of mud.

 

Great! Mentally stored away.

Did you put your meter to the battery? How did they suspect a bad alt?

 

The shop said the diodes in the alternator were bad. For some reason I didn't think to check the battery with a meter before taking it to the shop. Just thought I'd let the "pros" handle it and save me the time, I guess. I don't know how they figured the diodes were bad. If that is even a real thing?

 

And this is all there was of mud on the outside. The engine was pretty muddy though. Maybe hosing off the underbody and wheel wells after is what messed up the alternator.

 

For some enlightenment about diodes, read this :
http://www.knowyourparts.com/technical-articles/starters-and-alternators-common-misdiagnosis/

 

I have got mine a lot muddier quite often. But I never hose off my engine, I just let nature do it...

 

Initially I only hosed off the undercarriage and wheel wells. Then the light came on the next day. Maybe with 125k on the truck the alternator and/or diodes were about dead anyway and this just pushed them over the edge. I suspect the watery mud that splashes up and coats the engine can mess with things more than sticky mud.

Thanks for the article tan4x4. Very informative.